1. Field of the Invention
The present invention relates to fluidized solid catalytic conversions of hydrocarbons wherein a fluidized solids catalytic reactor is employed which has a plurality of risers and a common regeneration zone and wherein different reactions are carried out in the risers. In particular, the invention provides for the conversion of hydrocarbon streams which are of relatively low value to high value oxygenated fuels by a novel procedure which involves several catalytic conversion reactions using the same catalyst in separate risers in a fluidized solids catalytic reactor with a common regeneration zone in combination with an etherification reaction to convert iso-alkenes formed in one or both of the risers to high octane ethers such as methyl tertiary butyl ether (MTBE) and tertiary amyl methyl ether (TAME).
2. Description of the Prior Art
The use of fluidized solids catalytic reactors with multiple users is quite well known. Illustrative patents describing such operations include U.S. Pat. Nos. 4,966,681, 4,606,810, 3,748,251, 3,849,291, 3,894,931, 3,894,933, 3,894,934, 3,894,935, 3,926,778, 3,928,172, 3,974,062 and 4,116,814.
Various methods are known in the art for the conversion of branched olefins to the corresponding ether and/or alcohol. See U.S. Pat. Nos. 4,605,787, 4,575,566, 4,925,455, 4,957,709, 4,962,239, 4,967,020, 4,969,987, 4,830,685, 4,835,329, 4,827,045, 4,826,507, 4,814,519, 5,001,292, 5,003,112 and the like.
Likewise, methods are known whereby linear olefins can be converted by skeletal isomerization to branched olefins. See, for example, U.S. Pat. Nos. 4,037,029, 4,793,984, 4,683,217, 4,973,785, 4,882,038, 4,758,419, 4,500,651, 4,973,460 and the like.
Various integrated processes for the conversion of hydrocarbons to gasoline components which involve etherification of branched tertiary C.sub.4 and/or C.sub.5 olefins are also known. See, for example, U.S. Pat. Nos. 4,988,366, 4,925,455, 4,957,709, 4,969,987, 4,830,635, 4,835,329, 4,827,045, 4,826,507, 4,854,939, 5,001,292, 4,857,667, 5,009,859, 5,015,782, 5,013,329 and the like.
European publication 0 026,041 describes a process for producing olefins and/or ethers of high octane number from a wide C.sub.2 to C.sub.10 olefinic stream. The wide olefinic feedstock is restructured over a zeolite catalyst to form primarily C.sub.4 to C.sub.7 olefins, the C.sub.4 to C.sub.7 iso-olefins are reacted with methanol to form high octane ethers and unreacted olefins and methanol are separated from the ether product and recycled to the restructuring operation.
U.S. Pat. No. 4,814,519 shows a two-stage process for the production of ethers from olefin-containing feedstock such as from an FCC unit whereby the feedstock is reacted under conditions to maximize production of C.sub.4 -C.sub.5 iso-olefins, particularly tertiary iso-olefins. The resulting iso-olefin rich product is then subjected to a catalytic etherification reaction to produce ethers such as TAME.